MOLECULAR-CLONING, SEQUENCE-ANALYSIS, AND EXPRESSION OF THE GENE ENCODING THE IMMUNODOMINANT 32-KILODALTON PROTEIN OF COWDRIA-RUMINANTIUM

Cowdria ruminantium, the causative agent of heartwater disease, expres ses an immunodominant and conserved 32-kilodalton protein (MAP1; forme rly called Cr32), which is currently in use for serodiagnosis of the d isease. The gene encoding this protein, designated map1, was detected, cloned, and characterized. The gene is conserved between four differe nt stocks of C. ruminantium originating from Senegal, Sudan, South Afr ica, and Zimbabwe. Homology searches revealed MAP1 to be homologous to the Anaplasma marginale surface protein MSP4, a potential protective antigen. The MAP1 protein, expressed in Escherichia coli fused with gl utathione S-transferase, is specifically recognized by sera from anima ls infected with seven different stocks of C. ruminantium.